Air responsive delay arming device



May 14, 1968 F. H. SWAIM AIR RESPONSIVE DELAY ARMING DEVICE Filed Jan. 31, 1967 INVENTORQ Frank H. Swaim ATT NEY United States Patent 3,382,805 AIR RESPONSIVE DELAY ARMING DEVICE Frank H. Swaim, Silver Spring, Md., assiguor to the United States of America as represented by the Secretary of the Navy Filed Jan. 31, 1967, Ser. No. 613,051 2 Claims. (Cl. 10281.2)

ABSTRACT OF THE DISCLOSURE An air-flow actuated delay arming device having a resiliently urged air scoop extendable into a slip stream to a magnitude determined by the equilibrium of the slip-stream and resilient forces acting thereon. The magnitude of extension varies the degree of registry between an orifice and a duct thereby maintaining constant the amount of air-flow impinging upon the blades of a turbine, the revolution rate of which controls the amount of time delay. A detent-mechanism is provided for locking the scoop in a fully extended position in response to a large inertia force.

Background of the invention The invention described herein may be manufactured and used by or for the Government of the United States of America for government purposes without the payment of any royalties thereon or therefor.

This invention relates generally to air-responsive actuatiug mechanisms for moving vehicles and more particularly to an air-flow responsive delay arming device for an aerial bomb fuze.

In aerial bombardment, it is a common safety practice to provide for delay arming of the bomb until the distance between the launching aircraft and the launched bomb is sufiicient to prevent damage to the aircraft by the detonation of the bomb on arming. Diverse air-responsive timing devices have been developed to provide the necessary time delay. Although these devices have performed satisfactorily the widespread use of both propeller and jet aircraft for bombing purposes has created a need for a versatile timing device which will provide a constant time delay irrespective of significant differences in launching speeds. Additionally, the various modes of bomb-launching i.e., retarded and unretarded, presently employed has accentuated the need for such a timing device to provide the relatively longer and shorter delay arming periods required for retarded and unretarded bomb launchings.

Summary of the invention It is therefore one object of this invention to provide a variable time actuating device for moving vehicles.

Another object of the instant invention is the provision of a device exhibiting a constant delay arming time for a moving vehicle irrespective of the air-stream velocity acting thereon.

A further object of this invention is to provide a delay arming device selectively responsive to slip-stream velocities or inertia forces.

Still another object of the present invention is the provision of a variable delay arming device for an aerial bomb.

In accordance with the preferred embodiment of this invention, these and other objects are attained by a delay arming device having an air-scoop resiliently urged to assume a position in the slip-stream of a moving vehicle which is determined by the equilibrium of the slip-stream and resilient forces thereby regulating the flow of air to a constant magnitude through an aperture to be channelled to a revolving utilization device.

Patented May 14, 1968 A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein: a

FIG. 1 is a view, partially in section, of the air arming delay mechanism in an aerial bomb;

FIG. 2 is a frontview of the scoop assembly of the air arming delay mechanism; and

FIG. 3 is a side view of the scoop assembly of the air arming delay mechanism.

Description of the preferred embodiment Referring now to the drawings wherein like reference characters designate identical parts throughout the several views, and more particularly to FIG. 1, whereon is shown a conventional aerial bomb 11 having a plurality of fins 12 pivotally mounted on its after portion, a conventional ordnance fuze 13, and a delay arming mechanism 14 according to the present invention. An air-driven turbine 15 is coupled through a shaft 16 to the fuze 13 for imparting rotational speeds to the fuze thereby to affect delayed fuze arming at times commensurate with the turbines speed of rotation. Fuze 13 may be of a conventional type which is provided with 'a governor, or clutch, retaining the fuze inactive until the turbine revolves at a certain rotational speed, 1200 r.p.m., for example, at which a maximum delay arming period of 5 seconds, for example, is effected which remains constant until the rotational speed reaches another speed, 1800 rpm. for example, at which a minimum delay arming period of 2.5 seconds, for example is effected. At this second speed, the clutch slips in response to any increase in rotational speed and the delay arming period remains constant at the minimum period.

As more clearly shown in FIGS. 2 and 3, the delay arming mechanism 14 includes an arcuately shaped semicylindrical scoop member 18 having an open end 19 and a closed end 21 rotatably mounted on a bearing 22 projecting from a body, or base, member 23 which may be an integral part of the bomb housing. A conforming cavity 24 is formed in body member 23 wherein the member 18 is slideably disposed. A shaft 25 is secured to base 23 by means of a threaded projection, or bolt 26, extending through an aperture 27 coacting with a nut 28. A resilient device, such as a coil spring 29, encircles shaft 25 having one end thereof seated in an end-slot 31 formed on the shaft and its other end extending in pressing engagement with the closed end 21 of scoop member 18 normally urging the open end, or mouth, 19 of scoop 18 to protrude beyond the bomb casing and into the slipstream. The bias of spring 29 may be adjusted by rotation of shaft 25 to other positions. An aperture 32 is formed in scoop member 18 which registers with one end of a duct or channel 33, the other end of Which is adjacent the blades of turbine 15. A vent nozzle 34 may be positioned in the bomb casing.

Bearing 22 may be provided with a Well 35 having a ball detent 36 disposed therein and urged outwardly by a coil spring 37 against scoop 18. An aperture 38 having a smaller diameter than the ball detent may be provided in scoop 18 for reception of the ball detent in response to an inertia force of a predetermined magnitude thereby to lock the scoop in a fully extended position.

In operation, bomb 11 may be launched either with the bomb fins 12 retracted, as shown, or with the fins extended, as shown in broken-line construction whereby the fins act as an air brake.

Upon bomb launching in the unretarded mode with fins 12 retracted at a predetermined velocity of knots,

for example, the mouth of scoop 18 will be fully open to the slip-stream and aperture 32 will be in full registry with duct 33. At higher launching velocities, 600 knots, for example, or as the slip-stream velocity increases to this magnitude, the scoop mouth will rotate and recess into the bomb housing correspondingly as the urging force of coil spring 29 is overcome thereby moving aperture 32 out of register with duct 33. Thus, scoop 18 will pivot to assume a position in the slip-stream determined by the equilibrium of the forces of the air-stream and spring bias thereby varying the amount of air intake. Furthermore the pivoting of scoop 18 in response to these forces varies the degree of registry of aperture 32 with duct 33 in a manner that the amount of air-flow impinging upon the blades of turbine 15 is substantially constant thereby providing a constant delay arming period, of seconds, for example, for fuze 13 over a relatively wide range of launching velocities. Vent 34 provides for exhausting of the air-flow impinging upon the turbine blades.

If bomb launching is in the retarded mode, with fins 12 fully extended, the inertial shock of the slip-stream on the bomb fins will point scoop 18 to its fully extended position thereby aligning detent ball 36 with aperture 38 and effecting sealing of the ball within the aperture thereby locking the scoop in its fully extended position. Under this condition aperture 32 is in complete registry with duct, or channel member 33, and maximum air-flow to the blades of turbine results. The governor, or clutch, of fuze 12 slips when a predetermined speed of rotation is imparted to the turbine, i.e., 1800 r.p.m., for example, and the fuze will arm in a minimum period, i.e., 2.5 seconds, for example, which delay period will remain constant though the predetermined rotational speed may be exceeded.

Prior to launching, the bomb 11 is stowed in a bomb rack not shown, with the scoop 14 pressing against the rack and being fully recessed by the pressure of the bomb rack. Since the scoop 14 is fully recessed when stowed on an air craft prior to launching, the aperture 32 will be completely out of register with channel member 33, blocking air from the turbine blades. The air-flow to the blades of turbine 15 being thus blocked, there is no need for a safety device such as the usual p'ull wire to prevent the blades from rotating to prevent premature arming.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

What is claimed is:

1. A delay arming device for a moving vehicle comprising means rotatable to assume diverse extended positions relative to the slip-stream of the moving vehicle for taking in an amount of air proportional to the magnitude of extension,

means defining an aperture formed on said rotatable means,

channel means operatively associated with said aperture defining means for providing a fiow of air to a utilization device, said channel means and said aperture defining means being in complete registry when said rotatable means is in a fully extended position, and

resilient means normally urging said rotatable means to an extended position,

said rotatable means assuming a position determined by the equilibrium of the resilient and slip-stream forces acting thereon to vary the degree of registry of said aperture defining means and said channel means thereby providing a substantially constant fiow of air to the utilization device,

said rotatable means having an arcuate shaped semicylindrical member having an open end and a closed end,

means defining a second aperture formed on said rotatable means, and

resiliently urged detent means operatively coupled to said second aperture defining means, said detent means seating within said second aperture defining means in response to an inertial force on the moving vehicle thereby to lock said rotatable means in a fixed extended position.

2. A delay arming device for an aerial bomb comprising turbine means having a rate of rotation determined by the magnitude of air flow impinging thereon,

fuzing means having diverse delay arming periods corresponding to the rate of rotation of said turbine means, arcuate shaped means rotatably mounted in said bomb assuming diverse extended positions relative to the slip-stream about said bomb for taking in an amount of air proportional to the magnitude of extension,

means defining an aperture formed on said arcuate shaped means,

channel means operatively interconnecting said turbine means and said aperture defining means for effecting impingement of air flow on said turbine means, said channel means and said aperture defining means being in complete registry when said arcuate shaped means is in a fully extended position,

resilient means normally urging said arcuate shaped means to an extended position, said arcuate shaped means assuming a position determined by the equilibrium of the slip-stream and resilient forces acting thereon to vary the degree of registry of said aperture defining means and said channel means thereby providing a substantially constant flow of air to said turbine means,

means defining a second aperture formed in said arcuate shaped means, and

resiliently urged detent means operatively coupled to said second aperture defining means, said detent means seating within said second aperture defining means in response to an inertial force on said bomb thereby locking said arcuate shaped means in a fixed extended position.

References Cited UNITED STATES PATENTS 1,778,450 10/1930 Florez 137-499 2,701,526 2/1955 Rotkin l0270.2 2,749,833 6/1956 Hekelaar 137-499 2,766,964 10/1956 Almquist et al. 10281.2 X

BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner. 

